Hematocrit Sensor

Abstract

To provide a hematocrit sensor capable of accurately measuring a hematocrit value even in a blood circuit with various thicknesses and surface states.SOLUTION: A hematocrit sensor 6 for emitting light to liquid flowing in a conduit line having light permeability and measuring a hematocrit value on the basis of a signal acquired by receiving reflected light includes: a light emitting part for emitting light to liquid put in the conduit line through the conduit line; a light receiving part for receiving the light reflected by the liquid put in the conduit line through the conduit line; a fixing part having a groove for fixing the conduit line for fixing the light emitting part and the light receiving part outside the conduit line; and a data processing part for calculating a hematocrit value on the basis of a signal acquired from the light receiving part. The hematocrit sensor includes a hematocrit calculation part for calculating a hematocrit value on the basis of a blood signal and a reference signal, the reference signal being a signal obtained by putting any of physiological saline, dialysate solution, and air as a stage prior to putting blood in the conduit line, and the blood signal being a signal after putting blood in the conduit line.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a hematocrit sensor that is disposed in a blood flow path of a hemodialysis device that purifies a patient's blood while circulating it extracorporeally, and that measures the hematocrit value, which indicates the concentration of blood. [Background technology]

[0002] A hemodialysis device for performing dialysis treatment usually includes a blood circuit consisting of an arterial blood circuit and a venous blood circuit for circulating the patient's blood extracorporeally, a dialyzer connected to the arterial blood circuit and the venous blood circuit, respectively, as a blood purifier for purifying the blood circulating extracorporeally, and a water removal pump for removing excess water from the blood flowing through the dialyzer, thereby enabling blood purification treatment to be performed while removing water from the blood circulating extracorporeally through the blood circuit.

[0003] The amount of water to be removed during water removal (water removal speed) is controlled by controlling the operation of the water removal pump, but rapid or excessive water removal may excessively reduce the patient's circulating blood volume, which may lead to blood loss or shock, while a slow water removal speed may extend the overall treatment time, placing a strain on the patient. For this reason, for example, a blood concentration sensor or the like may be provided in the arterial blood circuit to continuously measure and monitor the concentration of blood circulating outside the body during treatment, particularly the hematocrit value, which is the volume fraction of blood cells (simply put, (red blood cell volume)÷((red blood cell volume)+(plasma))), thereby enabling efficient and safe treatment. A blood concentration sensor for measuring such hematocrit value is called a hematocrit sensor.

[0004] An example of the hemodialysis device is shown in FIG. 1. The blood circuit 1 is composed of an arterial blood circuit 1a and a venous blood circuit 1b mainly made of flexible tubes, and a dialyzer 2 is connected between the arterial blood circuit 1a and the venous blood circuit 1b. The arterial blood circuit 1a has an arterial puncture needle a connected to its tip, and a peristaltic blood pump 3 disposed in its middle. The venous blood circuit 1b has a venous puncture needle b connected to its tip, and a drip chamber (not shown), an air bubble detector (not shown), and the like connected in its middle. When the blood pump 3 is driven with the arterial puncture needle a and the venous puncture needle b punctured into the patient, the patient's blood passes through the arterial blood circuit 1a to the dialyzer 2, is hemodialyzed by the dialyzer 2, and returns to the patient's body through the venous blood circuit 1b. That is, the patient's blood is purified by the dialyzer 2 while being circulated extracorporeally through the blood circuit 1. The dialyzer 2 is connected to the arterial blood circuit 1a, the venous blood circuit 1b, and the dialysate inlet line 5a and the dialysate outlet line 5b, which are extended from the hemodialysis device 4. The dialyzer 2 contains a plurality of hollow fibers, the inside of which is the blood flow path, and the area between the outer peripheral surface of the hollow fibers and the inner peripheral surface of the housing is the dialysate flow path. The hollow fibers have a number of minute holes (pores) penetrating the outer peripheral surface and the inner peripheral surface to form a hollow fiber membrane, and are configured so that impurities in the blood can permeate into the dialysate through the hollow fiber membrane. The dialysis monitoring device 4 circulates the patient's blood while controlling the rotation speed of the blood pump 3, the circulation, drainage, and temperature of the dialysate, and performs blood purification treatment. Here, a hematocrit sensor 6 is disposed in the middle of the arterial blood circuit 1a to monitor the patient's blood condition during water removal.

[0005] Patent Document 1 discloses that the blood circulating outside the body through a blood circuit is irradiated with light such as infrared light through the blood circuit, the reflected light is received, and the hematocrit value is calculated based on the voltage (received light voltage) according to the amount of received light. At this time, a formula is used to calculate the hematocrit value from the received light voltage obtained in advance.

[0006] Patent Document 2 also discloses that the hematocrit value is corrected based on the flow rate per unit time before water removal by the water remover and the amount of water removed per unit time, since an offset occurs in the light receiving voltage due to differences in the type of blood circuit, manufacturing lot, etc. In correcting the hematocrit value, the offset amount of the blood circuit in the hematocrit sensor provided in the blood circuit upstream of the water remover and the hematocrit sensor provided in the blood circuit downstream of the water remover is considered to be the same, and correction is performed. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 4129867 [Patent Document 2] Patent No. 6621734 Summary of the Invention [Problem to be solved by the invention]

[0008] In the methods disclosed in Patent Documents 1 and 2, the offset amount of the received light voltage due to differences in thickness, material, etc. depending on the type of blood circuit, manufacturing lot, etc. is assumed to be a constant value regardless of the attachment position or attachment state of the blood circuit to the hematocrit sensor, and the hematocrit value is calculated.

[0009] However, in reality, even for blood circuits of the same type or manufacturing lot, the offset amount of the light receiving voltage changes depending on the attachment position of the hematocrit sensor. For example, the thickness and surface condition of the blood circuit may differ depending on the position of the blood circuit. As a result of the study by the present inventors, it has been found that the offset amount of the light receiving voltage in the near-infrared light region changes by up to about 9%. In addition, since the blood circuit is a flexible tube, the way in which it deforms when attached to the hematocrit sensor is not necessarily constant, it cannot be said that the reproducibility of the measurement is high. In other words, the methods of Patent Documents 1 and 2 cannot correct the change in the offset amount of the light receiving voltage caused by the blood circuit.

[0010] In addition, because the blood circuit is not a product designed for measurement with a hematocrit sensor, there is a large manufacturing variability relative to the measurement accuracy, so it is possible to use materials dedicated to measurement (such as non-flexible tubing materials). However, since dedicated measurement materials would be used for each treatment, additional costs would be incurred, and running costs would increase.

[0011] In view of the above problems, the present invention provides a hematocrit sensor capable of performing high-precision measurement even in blood circuits having various thicknesses and surface conditions. [Means for solving the problem]

[0012] The present invention, which solves the above problems, provides a hematocrit sensor that measures a hematocrit value based on a signal obtained by irradiating light onto a fluid flowing through a light-transmitting pipe and receiving reflected light, comprising: a light emitting unit that irradiates light onto the fluid filled in the pipeline through the pipeline; a light receiving unit that receives light irradiated from the light emitting unit and reflected by the fluid filled in the pipeline through the pipeline; a fixing portion having a groove for fixing the pipeline and for fixing the light emitting portion and the light receiving portion to the outside of the pipeline; a data processing unit that calculates a hematocrit value based on a signal obtained from the light receiving unit, The data processing unit includes: a data storage unit that fills the pipeline with any one of saline, dialysis fluid, and air as a preparatory step for filling the pipeline with blood, and stores the resulting signal as a reference signal; a data acquisition unit that acquires a signal after filling the duct with blood as a blood signal; and a hematocrit calculation unit that calculates a hematocrit value based on the blood signal and the reference signal.

[0013] In the hematric sensor of the present invention, the light-emitting unit includes a first light-emitting element that irradiates light including a first near-infrared light having an emission wavelength of 780 nanometers or more and 830 nanometers or less, the light receiving unit includes a first light receiving element that receives the first near-infrared light, The hematocrit calculation unit may calculate the hematocrit value according to the following formula (1). Ht=α2I 805(sub) 2 +α1I 805(sub) +β2I 805(div) 2 +β1I 805(div) +γ (1) Where: Ht: Hematocrit value α1, α2, β1, β2, γ: Coefficient I 805(sub) : (Blood signal by the first light receiving element) - (Reference signal by the first light receiving element) I 805(div) : (blood signal from the first light receiving element) / (reference signal from the first light receiving element).

[0014] The hematric sensor of the present invention includes a first light-emitting element that irradiates light including a first near-infrared light having an emission wavelength of 780 nanometers or more and 830 nanometers or less, and a second light-emitting element that irradiates light including a second near-infrared light having an emission wavelength of 1400 nanometers or more and 1600 nanometers or less, the light receiving unit includes a first light receiving element that receives the first near-infrared light and a second light receiving element that receives the second near-infrared light, The hematocrit calculation unit may calculate the hematocrit value according to the following formula (2). Ht=α 12 I 805(sub) 2 +α 11 I 805(sub) +β 12 I 1450(sub) 2 +β 11 I 1450(sub) +δ 11 I 805(sub) I 1450(sub) +α 22 I 805(div) 2 +α 21 I 805(div) +β 22 I 1450(div) 2 +β 21I 1450(div) +δ 21 I 805(div) I 1450(div) +γ (2) Where: Ht: Hematocrit value α 12 , α 11 , β 12 , β 11 , δ 11 , α 22 , α 21 , β 22 , β 21 , γ: coefficient I 805(sub) : (Blood signal by the first light receiving element) - (Reference signal by the first light receiving element) I 805(div) : (blood signal by the first light receiving element) / (reference signal by the first light receiving element) I 1450(sub) : (Blood signal by the second light receiving element) - (Reference signal by the second light receiving element) I 1450(div) : (blood signal from the second light receiving element) / (reference signal from the second light receiving element).

[0015] In the hematric sensor of the present invention, the conduit may be a flexible tube, and the height of the groove in the fixing part for fixing the conduit may be 85 to 95% of the diameter of the conduit.

[0016] The hematric sensor of the present invention may further include a display unit that detects that the conduit has been removed from the fixed portion and provides a display indicating that the reference signal should be measured again.

[0017] Further, the present invention for solving the above-mentioned problems provides a hematocrit measurement method for measuring a hematocrit value based on a signal output obtained by irradiating light onto a fluid flowing through a light-transmitting pipe and receiving reflected light, the method comprising the steps of: a data storage step of filling the pipeline with any one of saline, dialysis fluid, and air as a preparatory step for filling the pipeline with blood, and storing the obtained signal as a reference signal; a data acquisition step of acquiring a signal after filling the line with blood as a blood signal; and a hematocrit calculation step of calculating a hematocrit value based on the blood signal and the reference signal. Effect of the Invention

[0018] According to the present invention, when measuring the hematocrit value of blood flowing through an optically transparent pipe, the measurement can be performed with high accuracy even in pipes having various thicknesses and surface conditions. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic diagram illustrating a hemodialysis device. [Diagram 2] FIG. 2 is a perspective view illustrating the hematocrit sensor according to the present embodiment. [Diagram 3] FIG. 3 is a cross-sectional view illustrating the hematocrit sensor according to the present embodiment. [Figure 4] FIG. 4 is a graph showing the results of calculation of the hematocrit value for the same blood signal in the presence and absence of a reference signal. [Diagram 5] FIG. 5 is a schematic diagram illustrating the deformation of the blood circuit caused by the fixing portion of the hematocrit sensor. [Figure 6] FIG. 6 is a graph showing the calculation results of the hematocrit value when a flat portion was created and when it was not created. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The same reference numerals are used to denote the same materials, and the description of materials that have already been described will be omitted as appropriate. Note that the present invention is not limited to the embodiments described below.

[0021] As shown in FIG. 1, the hematocrit sensor 6 of this embodiment is attached to a part of a blood circuit 1 used in dialysis treatment, and measures the hematocrit value indicating the concentration of the patient's blood flowing through the blood circuit 1.

[0022] The structure of the hematocrit sensor 6 according to this embodiment is shown in FIG. 2. It is composed of a sensor module 9, a main body 10a, and a lid 10b. The blood circuit 1 is fitted into the groove of the main body 10a, and the lid 10b holds down and fixes the blood circuit 1. At this time, it is preferable that the depth of the groove of the main body 10a is 85 to 95% of the diameter of the blood circuit 1, and the blood circuit 1 is deformed when fixed with the lid. It is preferable that the main body 10a and the lid 10b are made of a material harder than the blood circuit 1, such as a resin or a metal. The first light-emitting element 7a, the second light-emitting element 7b, the first light-receiving element 8a, and the second light-receiving element 8b are attached to the sensor module 9, and are fixed in four holes provided in the main body 10a, as shown in FIG. 3. It is preferable that the first light-emitting element 7a and the second light-emitting element 7b are light-emitting diode elements or laser elements, etc., whose irradiated light has high directivity and whose emission wavelength is limited. The first light receiving element 8a and the second light receiving element 8b are photodiodes or the like. In this state, the first light emitting element 7a emits a first near infrared light, which is reflected by the fluid filled in the blood circuit 1 through the blood circuit 1 and received by the first light receiving element 8a. Similarly, the second light emitting element 7b emits a second near infrared light, which is reflected by the fluid filled in the blood circuit 1 through the blood circuit 1 and received by the second light receiving element 8b. The first light receiving element 8a and the second light receiving element 8b transmit a light receiving voltage according to the amount of light received to a data processing unit (not shown) of the hematocrit sensor 6. Here, the first near infrared light includes light having an emission wavelength of 780 nanometers or more and 830 nanometers or less, and more preferably includes an emission wavelength of 805 nanometers and has a narrow emission wavelength width. The second near-infrared light includes light having an emission wavelength of 1400 nanometers or more and 1600 nanometers or less, and more preferably includes an emission wavelength of 1450 nanometers and has a narrow emission wavelength range. In addition, the fluid includes blood, dialysis fluid, physiological saline, and air.

[0023] The method of measuring the hematocrit value by the hematocrit sensor 6 according to this embodiment will be described in detail below. First, the blood circuit 1 is filled with a fluid other than blood, and a light receiving voltage corresponding to the amount of light received by each of the first light receiving element 8a and the second light receiving element 8b is obtained and transmitted to the data processing unit. At this time, the light receiving voltage of the first light receiving element 8a is treated as a reference signal by the first light receiving element, and the light receiving voltage of the second light receiving element 8b is treated as a reference signal by the second light receiving element, and these are stored in a data holding unit (not shown) in the data processing unit. Next, the blood circuit 1 is filled with blood, and a light receiving voltage corresponding to the amount of light received by each of the first light receiving element 8a and the second light receiving element 8b is obtained and transmitted to the data processing unit. At this time, the light receiving voltage of the first light receiving element 8a is treated as a blood signal by the first light receiving element, and the light receiving voltage of the second light receiving element 8b is treated as a blood signal by the second light receiving element, and these are stored in a data acquisition unit (not shown) in the data processing unit. Thereafter, a hematocrit calculation unit (not shown) in the data processing unit calculates a hematocrit value based on the blood signal from the first light receiving element, the blood signal from the second light receiving element, the reference signal from the first light receiving element, and the reference signal from the second light receiving element, using a predetermined hematocrit calculation formula. This hematocrit calculation formula is shown in the following formula (2).

[0024] Ht=α 12 I 805(sub) 2 +α 11 I 805(sub) +β 12 I 1450(sub) 2 +β 11 I 1450(sub) +δ 11 I 805(sub) I 1450(sub) +α 22 I 805(div) 2 +α 21 I 805(div) +β 22 I 1450(div) 2 +β 21 I 1450(div) +δ 21 I 805(div) I 1450(div) +γ (2) Where: Ht: Hematocrit value α12 , α 11 , β 12 , β 11 , δ 11 , α 22 , α 21 , β 22 , β 21 , γ: coefficient I 805(sub) : (Blood signal by the first light receiving element) - (Reference signal by the first light receiving element) I 805(div) : (blood signal by the first light receiving element) / (reference signal by the first light receiving element) I 1450(sub) : (Blood signal by the second light receiving element) - (Reference signal by the second light receiving element) I 1450(div) : (blood signal from the second light receiving element) / (reference signal from the second light receiving element).

[0025] It is preferable that the cover portion 10b is not removed between the acquisition of the reference signal by the first light receiving element and the reference signal by the second light receiving element and the acquisition of the blood signal by the first light receiving element and the blood signal by the second light receiving element, and if it is removed, it is preferable that the removal be detected and a display be displayed to prompt the reference signal to be acquired again.

[0026] Hereinafter, it will be shown that this embodiment allows highly accurate measurement even in blood circuits with various thicknesses and surface conditions.

[0027] The hematocrit sensor determines the hematocrit value by electro-optically quantifying the components, utilizing the property that each component of blood, such as red blood cells and plasma, has its own unique light absorption property. Here, regarding the absorption of hemoglobin, which is the main component of red blood cells, the absorbance of oxygenated hemoglobin and deoxygenated hemoglobin is equal at a wavelength of 805 nanometers. Therefore, the first near-infrared light having an emission wavelength of 780 nanometers or more and 830 nanometers or less near 805 nanometers can suitably quantify the amount of red blood cells without being affected by whether the hemoglobin is oxygenated hemoglobin or deoxygenated hemoglobin. On the other hand, water, which is the main component of blood plasma, has an absorption from 1200 nanometers to 1600 nanometers, and has a peak of absorbance especially at 1450 nanometers. Therefore, the second near-infrared light having an emission wavelength of 1400 nanometers or more and 1600 nanometers or less can suitably quantify the amount of blood plasma. That is, by using the second near-infrared light in addition to the first near-infrared light, the hematocrit value, which is the volume fraction of blood cells, can be measured with high accuracy.

[0028] Next, calculation of the hematocrit value from a calculation formula based on the acquired blood signal and reference signal will be described.

[0029] After the blood circuit 1 is attached to the fixing part 10 consisting of the main body part 10a and the lid part 10b, the data storage part acquires a reference signal in a state filled with either physiological saline before blood is filled, dialysis fluid, or air, and stores the data until the lid part 10b is removed. That is, the data storage part acquires and stores data including the optical characteristics of the blood circuit 1 in a state where there is no blood. For example, when the thickness of the blood circuit 1 (wall thickness of the tube) is thick, the light receiving voltage becomes high. This is caused by the reflected light through the tube of the blood circuit 1 on the sensor module 9 side.

[0030] Next, the data acquisition unit acquires a blood signal after filling the blood circuit 1 with blood. The acquired blood signal has a signal intensity according to the hematocrit value, and also has a value including the optical characteristics of the blood circuit 1.

[0031] The hematocrit calculation unit calculates the hematocrit value based on the blood signal acquired by the data acquisition unit at any time and the reference signal stored by the data storage unit (see formula (2)). Since the blood signal is a value including the hematocrit value and the optical characteristics of the blood circuit 1, the blood signal is corrected using the reference signal, which is data including the optical characteristics of the blood circuit 1 in a state where there is no blood. In order to remove the influence of such optical characteristics, it is common to divide the blood signal by the reference signal, but in this embodiment, the accuracy was not improved. The inventors have conducted extensive research and found that the optical characteristics of the blood circuit 1 are greatly influenced by the reflected light through the tube of the blood circuit 1 on the sensor module 9 side. As this is constant regardless of the fluid, a term was introduced to subtract the blood signal by the reference signal. Next, as for the hematocrit calculation formula itself, in consideration of the difficulty of accurately modeling this phenomenon, a polynomial approximation was used. Since the coefficients of the polynomial are obtained experimentally, in this embodiment, a quadratic expression is preferable in relation to the number of experimental data, and the approximation was used with formula (2). However, if there is a large amount of experimental data, a cubic or quartic equation may be used. When obtaining experimental data, it is natural to increase the number of types of blood circuits 1, and it is preferable to obtain blood from a large number of samples. Using equation (2) obtained in this way, the hematocrit value is continuously monitored during actual dialysis treatment.

[0032] FIG. 4 shows the calculation results of the hematocrit value when there is no reference signal and when there is a reference signal for the same blood signal. The vertical axis is the calculated hematocrit value in this embodiment, and the horizontal axis is the measured value by the microhematocrit method. Three types of blood circuits 1 are used, and it shows that using a reference signal allows the hematocrit value to be measured more accurately regardless of the blood circuit 1. In this way, by performing calculations using the reference signal obtained in the data storage unit, the influence of the optical characteristics of the blood circuit 1 can be reduced.

[0033] In this embodiment, the first near-infrared light and the second near-infrared light are used, but as described above, since the first near-infrared light directly captures the amount of red blood cells, it is possible to measure using only the first near-infrared light, although the measurement accuracy is inferior to that when the first near-infrared light and the second near-infrared light are used. In that case, the number of light-emitting elements and light-receiving elements can be reduced compared to when the first near-infrared light and the second near-infrared light are used, thereby reducing the cost of the device. The hematocrit calculation formula (2) is as shown in the following formula (1).

[0034] Ht=α2I 805(sub) 2 +α1I 805(sub) +β2I 805(div) 2 +β1I 805(div) +γ (1) Where: Ht: Hematocrit value α1, α2, β1, β2, γ: Coefficient I 805(sub) : (Blood signal by the first light receiving element) - (Reference signal by the first light receiving element) I 805(div) : (blood signal from the first light receiving element) / (reference signal from the first light receiving element).

[0035] Next, the reason why the groove depth of the main body 10a is 85 to 95% of the diameter of the blood circuit 1 and the blood circuit 1 is deformed when fixed with the lid 10b will be described with reference to FIG. 5. According to this embodiment, the blood circuit 1 is pressed so as to contact the main body 10a and the lid 10b, forming a flat portion. The light is irradiated and received at this formed flat portion, so that the reproducibility of the light irradiation and light reception phenomena in the hematocrit sensor is increased. If the flat portion is not sufficiently generated, the curvature of the blood circuit 1 must be taken into consideration depending on the installation position of the blood circuit 1, and the light irradiation and light reception phenomena will change from when formulas (1) and (2) are experimentally obtained, making it impossible to maintain accuracy. The inventors have conducted extensive research, and have determined the effects on dialysis treatment (such as obstruction of blood flow) caused by misalignment of the blood circuit 1 and squeezing the blood circuit 1 too much, as well as the conditions for forming a sufficient flat portion, and have concluded that it is preferable to set the groove depth of the main body part 10a to 85 to 95% of the diameter of the blood circuit 1. This value varies depending on the installation distance of each element in the sensor module 9, but the technical essence is to ensure reproducibility in hematocrit measurement by creating a flat portion on the blood circuit 1 and realizing light irradiation and light reception there. Figure 6 shows the calculation results of the hematocrit value when a flat portion is created and when it is not created. In addition, in order to evaluate the variation in data in the evaluation of the reproducibility of the attachment, it was determined that artificial blood that can obtain a light receiving voltage equivalent to blood is sufficient, and the light receiving voltage was converted to a hematocrit value equivalent. The vertical axis shows the difference between the maximum and minimum values ​​when the blood circuit 1 is attached to the main body part 10a and the light receiving voltage is measured 10 times. This shows that creating a flat section with a groove depth of 91% of the diameter of the blood circuit 1 increases the reproducibility of the installation of the blood circuit 1 and enables accurate measurement of the hematocrit value. In this way, by creating a flat section by squeezing with the groove depth, the influence of the optical properties of the blood circuit 1 can be reduced.

[0036] Furthermore, in this embodiment, a display unit is provided that detects that the blood circuit 1 has been removed from the hematocrit sensor 6, and displays a message to remeasure the reference signal, which is the signal output before blood was filled into the blood circuit 1, and update the data in the data storage unit. For example, removal of the blood circuit 1 may be detected based on a change in the received light voltage, or a visible light projector / receiver unit dedicated to detecting whether the blood circuit 1 is attached may be added to detect removal of the blood circuit 1. This hematocrit sensor is based on the premise that there is no difference in the optical characteristics of the blood circuit 1 when acquiring the reference signal and the blood signal, so adding this function makes it possible to maintain measurement accuracy.

[0037] Thus, according to this embodiment, there is no need for components dedicated to measurement (such as non-flexible tubing materials) and measurements can be performed on a general-purpose blood circuit, reducing the number of parts and lowering running costs. Of course, it is also possible to improve measurement accuracy by using components dedicated to measurement. [Industrial Applicability]

[0038] The present invention is not limited to dialysis monitoring devices, but can also be applied to devices that circulate blood through tubes, such as artificial heart-lung machines, and can be widely applied to other blood circulation devices, but the scope of application is not limited to these. [Explanation of symbols]

[0039] 1 Blood circuit 1a Arterial blood circuit 1b Venous blood circuit 2 Dialyzer 3. Blood Pump 4 Dialysis monitoring device 5a Dialysis fluid introduction line 5b Dialysis fluid drain line 6 Hematocrit Sensor 7 Light emitting part 7a First light emitting element 7b Second light-emitting element 8 Light receiving section 8a First light receiving element 8b Second light receiving element 9 Sensor Module 10 Fixed part 10a Main body 10b Lid

Claims

1. A hematocrit sensor that measures a hematocrit value based on a signal obtained by irradiating light onto a fluid flowing through an optically transparent pipe and receiving reflected light, comprising: a light emitting unit that irradiates light onto the fluid filling the pipeline through the pipeline; a light receiving unit that receives light irradiated from the light emitting unit and reflected by the fluid filled in the pipeline through the pipeline; a fixing portion having a groove for fixing the pipeline and for fixing the light emitting portion and the light receiving portion to the outside of the pipeline; a data processing unit that calculates a hematocrit value based on a signal obtained from the light receiving unit; Equipped with The data processing unit includes: a data storage unit that fills the pipeline with any one of physiological saline, dialysis fluid, and air as a preparatory step for filling the pipeline with blood, and stores the resulting signal as a reference signal; a data acquisition unit that acquires a signal after the blood is filled into the pipeline as a blood signal; a hematocrit calculation unit that calculates a hematocrit value based on the blood signal and the reference signal; A hematocrit sensor comprising:

2. The light emitting unit includes a first light emitting element that irradiates light including a first near-infrared light having an emission wavelength of 780 nanometers or more and 830 nanometers or less, the light receiving unit includes a first light receiving element that receives the first near-infrared light, The hematocrit sensor according to claim 1 , wherein the hematocrit calculation section calculates the hematocrit value according to the following formula (1): Ht=a ２ I ８０５（ｓｕｂ） ２ +a １ I ８０５（ｓｕｂ） +b ２ I ８０５（ｄｉｖ） ２ +b １ I ８０５（ｄｉｖ） +c ・・・(1) Where: Ht: Hematocrit value a １ ,a ２ 、b １ 、b ２ 、c:coefficient I ８０５（ｓｕｂ） : (Blood signal by first light receiving element) - (Reference signal by first light receiving element) I ８０５（ｄｉｖ） : (Blood signal by first light receiving element) / (Reference signal by first light receiving element)

3. The light emitting unit includes a first light emitting element that irradiates light including a first near-infrared light having an emission wavelength of 780 nanometers or more and 830 nanometers or less, and a second light emitting element that irradiates light including a second near-infrared light having an emission wavelength of 1400 nanometers or more and 1600 nanometers or less, the light receiving unit includes a first light receiving element that receives the first near-infrared light and a second light receiving element that receives the second near-infrared light, The hematocrit sensor according to claim 1 , wherein the hematocrit calculation section calculates the hematocrit value according to the following formula (2): Ht=a １２ I ８０５（ｓｕｂ） ２ +a １１ I ８０５（ｓｕｂ） +b １２ I １４５０（ｓｕｂ） ２ +b １１ I １４５０（ｓｕｂ） +d １１ I ８０５（ｓｕｂ） I １４５０（ｓｕｂ） +a ２２ I ８０５（ｄｉｖ） ２ +a ２１ I ８０５（ｄｉｖ） +b ２２ I １４５０（ｄｉｖ） ２ +b ２１ I １４５０（ｄｉｖ） +d ２１ I ８０５（ｄｉｖ） I １４５０（ｄｉｖ） +γ・・・(2) Where: Ht: Hematocrit value a １２ ,a １１ 、b １２ 、b １１ 、d １１ ,a ２２ ,a ２１ 、b ２２ 、b ２１ 、c:coefficient I ８０５（ｓｕｂ） : (Blood signal by first light receiving element) - (Reference signal by first light receiving element) I ８０５（ｄｉｖ） : (Blood signal by first light receiving element) / (Reference signal by first light receiving element) I １４５０（ｓｕｂ） : (Blood signal by the second light receiving element) - (Reference signal by the second light receiving element) I １４５０（ｄｉｖ） : (blood signal by second light receiving element) / (reference signal by second light receiving element)

4. the conduit is a flexible tube, 4. The hematocrit sensor according to claim 1, wherein the height of the groove in the fixing portion for fixing the conduit is 85 to 95% of the diameter of the conduit.

5. 5. The hematocrit sensor according to claim 1, further comprising a display unit that detects when the conduit is removed from the fixing unit and displays a message to recommend that the reference signal be measured again.

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